Why earthenware is still used
Pots made of fired clay are among the oldest cooking vessels in Mexico, and they remain in daily use in many homes and markets. Their appeal is practical. Earthenware heats slowly and releases heat slowly, which suits long simmering. Many cooks also feel that beans, stews, and sauces taste better from clay, although that is a matter of preference, not a measured fact.
Two shapes are especially common. The olla is a deep, round-bellied pot with a narrow neck, used for beans, broths, and atole. The cazuela is wider and shallower, with a broad opening, and is used for stews, braises, sauces, and dishes that need stirring or reducing. Both come in sizes from single-serving bowls to pots large enough for a party.
Glazed and unglazed clay
Clay cookware is generally sold either glazed or unglazed. A glazed cazuela has a glassy coating, often on the inside, that makes it less porous and easier to clean. Unglazed pieces absorb liquid and can pick up flavours, and they are more often used for things like comals or for water jars.
The most important safety point concerns the glaze. Traditional low-fired glazes have, in some places and periods, contained lead, which can leach into food, especially acidic or long-simmered dishes such as tomato sauces or fruit-based preparations. Buy cookware that is clearly marked lead-free or food-safe, and treat inexpensive decorative pieces as decoration only. If you cannot tell what a glaze contains, it is safer not to cook in it.
Curing a new pot
Curing, sometimes called seasoning, is meant to strengthen the clay and reduce the risk of cracking. Methods vary by region, family, and the kind of pot, and there is no single correct way. Commonly described steps include:
- Wash the pot gently with warm water and a soft brush, without strong detergent that the clay might absorb.
- Soak it in water for a good while, often several hours or overnight, so the clay takes up water.
- Dry it completely.
- Rub the inside with a cut garlic clove, which some cooks say helps seal the surface.
- Heat gently with water inside, sometimes with a little rice, masa, or flour mixed into the liquid, and let it simmer on low heat before discarding the liquid.
Follow any instructions from the maker first, since they know the clay. Glazed pieces sometimes need only washing and a gentle first heating.
Heating without cracking
Cracking is almost always caused by sudden changes in temperature. A few habits help:
- Start on the lowest heat and increase gradually.
- Always keep some liquid or oil in the pot while it is on the heat. An empty clay pot over a flame is at risk.
- Use a flame diffuser on a gas ring, or a low flame that does not lick up the sides.
- Never put a hot pot on a cold, wet surface, and never add cold liquid to a very hot pot.
- Check whether the pot is rated for your stove. Some are suited to gas or open fire but not to electric coils or induction.
What suits a clay pot
Earthenware does well with slow, moist cooking. Pot beans are the classic example, and a long, gentle simmer in an olla is a common way to get tender beans with a creamy broth. Cazuelas are also used for mole de olla and other vegetable-rich stews, for rice dishes, for braises, and for reheating sauces. Frying is less common because clay does not tolerate sudden temperature swings from hot oil.
Some dishes are even served in the cooking vessel at the table, which keeps them warm. In many households a favourite pot is kept for a single purpose, such as beans only.
Cleaning and storage
Let the pot cool before washing, then use warm water and a soft brush. Many cooks avoid strong detergents on unglazed clay, since the material can absorb them. Dry thoroughly before putting it away, and store it in a ventilated place, because a pot stored damp may smell musty or grow mould. If a smell lingers, a simmer with water and a little baking soda is a common remedy, though a badly cracked or leaking pot should be retired.
Hairline cracks are a judgement call. A fine crack that does not leak may still be used by some cooks, but a pot that seeps or has a deepening crack is better replaced.
A note on expectations
A clay pot will not make poor ingredients taste wonderful, and it requires more patience than a modern stainless pot. What it offers is gentle, steady heat and a familiar, traditional way of cooking, one that connects the cook to long-standing practice in many parts of Mexico. Treat it carefully and it can last many years.